1. Field of the Invention
This invention relates to devices for holding open a surgical cavity.
2. Description of the Prior Art
In U.S. Pat. Nos. 5,081,983 and 5,183,032 and the allowed U.S. patent application Ser. No. 08/149,066, all owned by the assignee hereof: we have described different medical retractors for use in holding open body cavities including surgical cavities in humans or animals. A variety of retractors have been provided in addition to the retractors described in the aforementioned retractors. For example, various retractors are disclosed in the following U.S. Pat No. 3,750,652 issued to Sherwin; U.S. Pat. No. 4,130,113 issued to Graham; and U.S. Pat. No. 4,667,657 issued to Kulik et at. The Sherwin retractor includes a pair of blades used to separate a patient's knee with the blades being forcefully driven apart by means of a worm gear. The Graham Patent discloses a plurality of flesh engaging blades arranged on a circular frame through which the surgeon operates. Finally, the Kulik et al. Patent discloses a plurality of blades movable apart by means of a rod slidably mounted to the retractor frame. Foreign patents include Italian Patents 445162 and 464302; British Patent 330629; French Patent 542744; and German Patent 1700. The two Italian patents disclose a plurality of blades inserted into the cavity along with a stationary plate. Wing nuts or other members protrude outwardly from the retractor allowing the surgeon to possibly snag the surgical gloves thereon. The British patent discloses a plurality of blades mounted to a ring structure through which the surgeon examines the patient. The French patent also discloses a plurality of blades mounted to a ring shape frame. Finally, the German patent discloses an expandable retractor which utilizes a worm gear projecting to the side of the retractor frame.
In order to facilitate the use of a retractor, it is desirable that one person be able to easily manipulate the various blades of the retractor for insertion into the surgical cavity. It is therefore desirable that the blades be mounted on a relatively simple frame. The U.S. Pat. No. 3,038,468 issued to Raeuchle, U.S. Pat. No. 3,724,449 issued to Gauthier and U.S. Pat. No. 5,299,563 issued to Seten all disclose frames having a plurality of retractor blades mounted thereto.
Despite the medical retractors provided to date, there is still need for a retractor which may be used by a surgeon without assistance from another with the surgeon being able to gradually open the wound, incision or body cavity to the desired size. Such a retractor and method of holding open the cavity must ensure that the retractor is stable relative to the patient and does not become accidentally dislodged.
A major disadvantage of the prior retractors is that the structures typically provide for a variety of fasteners and other elements which protrude outwardly above the retractor snagging the surgeons glove and surgical thread. Thus, there is a need for a retractor having a smooth flat upwardly facing surface with the retractor resting atop the patient in a stable manner while the blades protrude downwardly into the cavity. Disclosed herein is such a retractor.